Assessment of minimum target dose as a predictor of local failure after spine SBRT

OBJECTIVES

Metastasis-directed stereotactic body radiation therapy (SBRT) has demonstrated robust clinical benefits in carefully selected patients, improving local control and even overall survival (OS). We assess a large database to determine clinical and dosimetric predictors of local failure after spine SBRT.

METHODS

Spine SBRT treatments with imaging follow-up were identified. Patients were treated with a simultaneous integrated boost technique using 1 or 3 fractions, delivering 20-24 Gy in 1 fraction to the gross tumor volume (GTV) and 16 Gy to the low dose volume (or 27-36 Gy and 21-24 Gy for 3 fraction treatments). Exclusions included: lack of imaging follow-up, proton therapy, and benign primary histologies.

RESULTS

522 eligible spine SBRT treatments (68 % single fraction) were identified in 377 unique patients. Patients had a median OS of 43.7 months (95 % confidence interval: 34.3-54.4). The cumulative incidence of local failure was 10.5 % (7.4-13.4) at 1 year and 16.3 % (12.6-19.9) at 2 years. Local control was maximized at 15.3 Gy minimum dose for single-fraction treatment (HR = 0.31, 95 % CI: 0.17 - 0.56, p < 0.0001) and confirmed via multivariable analyses. Cumulative incidence of local failure was 6.1 % (2.6-9.4) vs. 14.2 % (8.3-19.8) at 1 year using this cut-off, with comparable findings for minimum 14 Gy. Additionally, epidural and soft tissue involvement were predictive of local failure (HR = 1.77 and 2.30).

CONCLUSIONS

Spine SBRT offers favorable local control; however, minimum dose to the GTV has a strong association with local control. Achieving GTV minimum dose of 14-15.3 Gy with single fraction SBRT is recommended whenever possible.

A Single Arm Phase 2 Trial of Trametinib in Patients With Locally Advanced or Metastatic Epithelioid Hemangioendothelioma

PURPOSE

Epithelioid hemangioendothelioma (EHE) is a rare vascular cancer with pathogenic TAZ-CAMTA1 operating as an oncogenic driver through activation of MAPK pathway. Trametinib is an inhibitor of MEK, a critical kinase in the MAPK pathway. We sought to evaluate the effect of trametinib in patients with EHE.

PATIENTS AND METHODS

A phase 2 trial of trametinib was conducted in patients with locally advanced or metastatic EHE. Eligibility requirements included evidence of tumor progression or presence of EHE-related pain requiring opiates for management prior to enrollment. The primary endpoint was objective response rate (ORR) per RECIST1.1 in cases with TAZ-CAMTA1 confirmed by fusion-FISH. Secondary objectives were to estimate ORR for all patients, median PFS, 2-year OS rate, patient safety, and change in patient-reported global health and pain scores per PROMIS questionnaires.

RESULTS

44 patients enrolled and 42 started trametinib. TAZ-CAMTA1 was detected in 27 tumor samples. The ORR was 3.7% (95% CI: 0.094, 19.0), median PFS was 10.4 months (95% CI: 7.1, NA), and 2-year OS rate was 33.3% (95% CI: 19.1, 58.2) in the target population. Median pain intensity and interference scores improved significantly after 4 weeks of trametinib in patients using opiates. Common AEs related to trametinib were rash, fatigue, nausea/vomiting, diarrhea/constipation, alopecia and edema; one Grade 5 ARDS/pneumonitis was related to trametinib.

CONCLUSIONS

Trametinib was associated with reduction in EHE-related pain and median PFS of more than 6 months providing palliative benefit in patients with advanced EHE, but the trial did not meet the ORR goal.

Ripretinib versus sunitinib in gastrointestinal stromal tumor: ctDNA biomarker analysis of the phase 3 INTRIGUE trial

INTRIGUE was an open-label, phase 3 study in adult patients with advanced gastrointestinal stromal tumor who had disease progression on or intolerance to imatinib and who were randomized to once-daily ripretinib 150 mg or sunitinib 50 mg. In the primary analysis, progression-free survival (PFS) with ripretinib was not superior to sunitinib. In clinical and nonclinical studies, ripretinib and sunitinib have demonstrated differential activity based on the exon location of KIT mutations. Therefore, we hypothesized that mutational analysis using circulating tumor DNA (ctDNA) might provide further insight. In this exploratory analysis (N = 362), baseline peripheral whole blood was analyzed by a 74-gene ctDNA next-generation sequencing-based assay. ctDNA was detected in 280/362 (77%) samples with KIT mutations in 213/362 patients (59%). Imatinib-resistant mutations were found in the KIT ATP-binding pocket (exons 13/14) and activation loop (exons 17/18). Mutational subgroup assessment showed 2 mutually exclusive populations with differential treatment effects. Patients with only KIT exon 11 + 13/14 mutations (ripretinib, n = 21; sunitinib, n = 20) had better PFS with sunitinib versus ripretinib (median, 15.0 versus 4.0 months). Patients with only KIT exon 11 + 17/18 mutations (ripretinib, n = 27; sunitinib, n = 25) had better PFS with ripretinib versus sunitinib (median, 14.2 versus 1.5 months). The results of this exploratory analysis suggest ctDNA sequencing may improve the prediction of the efficacy of single-drug therapies and support further evaluation of ripretinib in patients with KIT exon 11 + 17/18 mutations. ClinicalTrials.gov identifier: NCT03673501.

Is Bone Marrow Aspiration and Biopsy of Clinical Importance in the Initial Staging of Extraskeletal Ewing Sarcoma?

BACKGROUND

Extraskeletal Ewing sarcoma are rare tumors within the Ewing sarcoma family. Initial staging studies for extraskeletal Ewing sarcoma historically have included imaging and bone marrow aspiration and biopsy (BMAB). However, recent studies on Ewing sarcoma of bone have questioned the utility of BMAB in the initial staging of patients, but no studies of which we are aware have evaluated the role of BMAB in extraskeletal Ewing sarcoma. We suspected that BMAB was of low diagnostic yield in patients with extraskeletal Ewing sarcoma and exposed patients to potential morbidity without an impact on their clinical course.

QUESTION/PURPOSE

Is BMAB a useful test in the staging of extraskeletal Ewing sarcoma?

METHODS

Between January 1996 and December 2021, our institution evaluated 109 patients with a listed diagnosis of extraskeletal Ewing sarcoma. Those patients were retrospectively reviewed for this study. Of those, we considered patients with biopsy-confirmed diagnosis of extraskeletal Ewing sarcoma. Biopsy was performed based on institutional protocols, with all diagnoses assigned by a board-certified pathologist. Based on that criteria, 96% (105 of 109) were eligible. An additional 18% (20 of 109) were excluded because records of their initial diagnostic and staging workup were not available. This left 78% (85 of 109) for analysis. Of those, 52% (44 of 85) were male. The average age was 32 ± 16 years. Primary tumor locations included extremities in 26% (22 of 85), paraspinal in 20% (17 of 85), chest in 19% (16 of 85), retroperitoneum in 13% (11 of 85), intraabdominal in 12% (10 of 85), intrapelvic in 7% (6 of 85), and head or neck in 4% (3 of 85). Initial diagnostic and staging information, including the use of PET-CT, bone scan, CT chest, and BMAB, was collected. Metastatic disease at the time of presentation or during follow-up was noted. The utility of BMAB was determined by the rate of positive tests in those undergoing BMAB during the initial staging process. Descriptive statistical analysis was sufficient to address the study question, and therefore no comparative statistics were performed.

RESULTS

BMAB was obtained during the initial staging process in 64% (54 of 85) of patients. This BMAB was negative in all 54 patients, including those with known metastatic disease.

CONCLUSION

Diagnosing metastatic disease in extraskeletal Ewing sarcoma is important as the presence of metastases at diagnosis adversely affects prognosis. The routine use of BMAB in the staging process of extraskeletal Ewing sarcoma is of low diagnostic yield. BMAB is unlikely to diagnose metastatic involvement even in patients with known metastases to bone. We do not have enough data to suggest whether other modalities, such as PET-CT, might be more useful. Similar studies should be pursued to determine the utility of the remainder of staging modalities in patients with extraskeletal Ewing sarcoma to elucidate the most efficient and effective staging protocol.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Patient-reported outcomes and tolerability in patients receiving ripretinib versus sunitinib after treatment with imatinib in INTRIGUE, a phase 3, open-label study

PURPOSE

In the INTRIGUE trial, ripretinib showed no significant difference versus sunitinib in progression-free survival for patients with advanced gastrointestinal stromal tumour (GIST) previously treated with imatinib. We compared the impact of these treatments on health-related quality of life (HRQoL).

PATIENTS AND METHODS

Patients were randomised 1:1 to once-daily ripretinib 150 mg or once-daily sunitinib 50 mg (4 weeks on/2 weeks off). Patient-reported outcomes were assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire for Cancer-30 (EORTC QLQ-C30) questionnaire at day (D)1, and D29 of all cycles until treatment discontinuation. Change from baseline was calculated. Time without symptoms or toxicity (TWiST) was estimated as the mean number of days without progression, death, or grade ≥3 treatment-emergent adverse events per patient over 1 year of follow-up.

RESULTS

Questionnaire completion at baseline was 88.1% (199/226) for ripretinib and 87.7% (199/227) for sunitinib and remained high for enrolled patients throughout treatment. Patients receiving sunitinib demonstrated within-cycle variation in self-reported HRQoL, corresponding to the on/off dosing regimen. Patients receiving ripretinib reported better HRQoL at D29 assessments than patients receiving sunitinib on all scales except constipation. HRQoL was similar between treatments at D1 assessments, following 2 weeks without treatment for sunitinib patients. TWiST was greater for ripretinib patients (173 versus 126 days).

CONCLUSION

Patients receiving ripretinib experienced better HRQoL than patients receiving sunitinib during the dosing period and similar HRQoL to patients who had not received sunitinib for 2 weeks for all QLQ-C30 domains except constipation. Ripretinib may provide clinically meaningful benefit to patients with advanced GIST previously treated with imatinib.

Local Control after Re-Irradiation of Spinal Metastases with Stereotactic Body Radiation Therapy

PURPOSE/OBJECTIVE(S)

Determine local control (LC) rate and risk of vertebral compression fractures (VCFs) and radiation myelitis (RM) for patients receiving re-irradiation of spinal metastases (SMs) using stereotactic body radiation therapy (SBRT) from large single-institutional experience with long follow-up.

MATERIALS/METHODS

Retrospectively identified patients receiving re-irradiation SBRT (rSBRT, 1, 3, or 5 fractions) to SMs previously treated with radiation therapy (RT) and having follow up imaging to assess local control. 1 fraction patients typically received 20-24 Gy and 16-18 Gy to the high- and low-risk planning target volumes (PTVs), respectively, and 27-39 Gy and 21-24 Gy for the 3 fraction patients, with a single level of 50 Gy for 5 fractions. Patient and treatment characteristics for previous RT (pRT) and rSBRT were collected, including histology and dose-volume histogram statistics (DVH). Kaplan-Meier estimates of overall survival (OS), and cumulative incidence (competing with death) of local failure with death as a competing risk was computed for the whole cohort and stratified by radioresistance of histology, and risk of VCF for RM (for treatments at L1 and above) and 95% confidence intervals. Equivalent dose in 2 Gy fractions (EQD2) for PTV and spinal cord (SC) DVH statistics was computed for each individual course and cumulatively, using a/b = 10 Gy for tumor and 2 Gy for SC.

RESULTS

Identified 107 lesions in 91 patients. 48 (45%) had radioresistant histologies. For all patients, at 1 and 2 years, respectively OS was 64% (55-74%) and 43% (34-55%), LC was 88% (81-94%) and 85% (78-91%) with median follow-up of 52 months (Table 1). OS and LC were not significantly different between radiosensitivity groups (p>0.05). Risk of VCF at 1 and 2 years was 7% (3-13%) and 9% (4-16%). RM was identified in 1 patient, who received 30 Gy in 5 fractions to T1, and had 1-fraction rSBRT 21 months later. SC Dmax was 31.5 Gy for pRT and 10.4 Gy, for rSBRT, resulting in total SC EQD2 of 73 Gy. RM was confirmed on MRI 8 months after rSBRT. Cumulative RM risk at 8 months after rSBRT was estimated at 1% (0-4%). Median EQD2 for the minimum dose to the high and low risk PTVs were 17.7 Gy (interquartile range, IQR, 13.0-27.6 Gy) and 13.7 Gy (IQR, 10.8-19.3 Gy) for rSBRT, and maximum EQD to SC for previous RT, rSBRT, and cumulatively was 38 Gy (IQR, 30-41 Gy), 27 Gy (IQR, 22-36 Gy), and 65 Gy (IQR, 54-73 Gy).Re-irradiation of spinal metastasis with SBRT can be delivered safely and provide high rates of local control, including for radioresistant tumors, as demonstrated with the longest reported follow-up in this setting.

CONCLUSION

Re-irradiation of SM with SBRT provides high rates of LC even for radioresistant tumors, and low risk of VCF and RM, based on the longest reported follow-up in this setting.

Assessment of Minimum Dose as a Strong Predictor of Local Failure after Spine SBRT

PURPOSE/OBJECTIVE(S)

Stereotactic body radiation therapy (SBRT) has demonstrated robust clinical benefits in carefully selected patients, improving local control and even overall survival (OS). Even so, a wide range of dose-fractionation schemes are used in clinical practice. We seek to assess a large database to determine clinical and dosimetric predictors of local failure after spine SBRT.

MATERIALS/METHODS

From a large institutional database, spine SBRT treatments with subsequent imaging follow-up to assess local control were identified. Patients were treated with a simultaneous integrated boost technique using 1 or 3 fractions, generally delivering 20-24 Gy in 1 fraction to the high dose volume and 16 Gy to the low dose volume (or 30-36 Gy and 24 Gy for 3 fraction treatments). Exclusions included: lack of imaging follow-up, proton therapy, and benign primary histologies. Statistical analyses included Cox proportional hazards analyses and the robust log-rank statistic for cut-point analysis. The cumulative incidence of local failure with death as a competing risk was considered as the primary endpoint.

RESULTS

A total of 522 eligible spine SBRT treatments (68% single fraction) were identified in 377 unique patients. Patients had a median OS of 43.7 months (95% confidence interval: 34.3-54.4). The cumulative incidence of local failure was 19.3% (15.3-23.2) at 1 year and 25.6% (21.1-29.9) at 2 years. Univariate analysis identified that the minimum dose (normalized for the prescription dose) was a strong predictor of local failure (p = 0.0093). Among patients treated with a single fraction, statistical significance was maintained (p = 0.024). No other dosimetric factors were predictive of local failure. In a cut point analysis, the log-rank statistic was maximized at 15.8 Gy minimum dose for single-fraction treatment (HR = 0.51, 95% CI: 0.34 - 0.75, p = 0.0009). Cumulative incidence of local failure was 15.1% (9.8-20.2) vs. 24.7% (17.2-31.5) at 1 year using this cut-off. Comparable local control was demonstrated with a minimum dose of 14 Gy (HR = 0.57, 95%: 0.37 - 0.87, p = 0.009), with reduced local control with lower minimum doses. Among a range of clinical factors assessed, only epidural and soft tissue involvement were predictive of local failure (HR = 1.80 and 1.98, respectively). Multivariable analyses incorporating soft tissue involvement, epidural extension, and multilevel disease confirmed the 15.8 Gy cutoff for single fraction cases (HR = 0.58, 95% CI: 0.38-0.88, p = 0.011).

CONCLUSION

Spine SBRT offers favorable local control using a range of dose-fractionation schemes; however, minimum dose has a strong association with local control, unlike any other dosimetric factors tested. Furthermore, statistical significance was maintained even when considering epidural extension and potential limitations from dose to the spinal cord. Our data suggests that the minimum dose should be prioritized during treatment planning, ideally to at least 14 - 15.8 Gy for single fraction.

Trimodality Therapy Improves Disease Control in Radiation-Associated Angiosarcoma of the Breast

PURPOSE

To evaluate the impact of trimodality treatment versus monotherapy or dual therapy for radiation-associated angiosarcoma of the breast (RAASB) after prior breast cancer treatment.

EXPERIMENTAL DESIGN

With Institutional Review Board approval, we identified patients diagnosed with RAASB and abstracted data on disease presentation, treatment, and oncologic outcomes. Trimodality therapy included (i) taxane induction, (ii) concurrent taxane/radiation, and then (iii) surgical resection with wide margins.

RESULTS

A total of 38 patients (median age 69 years) met inclusion criteria. Sixteen received trimodality therapy and 22 monotherapy/dual therapy. Skin involvement and disease extent were similar in both groups. All trimodality patients required reconstructive procedures for wound closure/coverage, compared with 48% of monotherapy/dual therapy patients (P < 0.001). Twelve of 16 (75%) patients receiving trimodality therapy had a pathologic complete response (pCR). With median follow-up of 5.6 years, none had local recurrence, 1 patient (6%) had distant recurrence, and no patients died. Among 22 patients in the monotherapy/dual therapy group, 10 (45%) had local recurrence, 8 (36%) had distant recurrence, and 7 (32%) died of disease. Trimodality therapy demonstrated significantly better 5-year recurrence-free survival [RFS; 93.8% vs. 42.9%; P = 0.004; HR, 7.6 (95% confidence interval, CI: 1.3-44.2)]. Combining all patients with RAASB regardless of treatment, local recurrence was associated with subsequent distant recurrence (HR, 9.0; P = 0.002); distant recurrence developed in 3 of 28 (11%) patients without local recurrence compared with 6 of 10 (60%) with local recurrence. The trimodality group had more surgical complications that required reoperation or prolonged healing.

CONCLUSIONS

Trimodality therapy for RAASB was more toxic but is promising, with a high rate of pCR, durable local control, and improved RFS.

Lack of radiosensitivity predicts poor disease specific survival in myxoid liposarcoma

BACKGROUND

Compared to other sarcomas, myxoid liposarcoma (ML) is known to be radiosensitive, with improved oncologic outcomes. Although these tumors "shrink" following radiotherapy, there is a paucity of data examining the degree of radiosensitivity and oncologic outcome. The purpose of the study was to evaluate pre- and postradiotherapy tumor volume to determine if size reduction impacts outcome.

METHODS

We reviewed 62 patients with ML undergoing surgical resection combined with preoperative radiotherapy, with pre- and postradiotherapy MRI. This included 34 (55%) males, with a mean age of 47 ± 14 years. All tumors were deep to the fascia, and 12 (19%) patients had tumors with a >5% round-cell component.

RESULTS

The mean volume reduction was 54% ± 29%. Compared to patients with >25% volume reduction, patients with reduction ≤25% had worse 10-year disease specific survival (86% vs. 37%, p < 0.01), in addition to an increased risk of metastatic disease (HR 4.63, p < 0.01) and death due to disease (HR 4.52, p < 0.01).

CONCLUSION

Lack of volume reduction is a risk factor for metastatic disease and subsequent death due to disease in patients with extremity ML treated with combined preoperative radiotherapy and surgery. This data could be used to stratify patients for adjuvant therapies and follow-up intervals.

Treatment outcomes of extraskeletal Ewing sarcoma

PURPOSE

Extraskeletal Ewing sarcoma (EES), is a rare soft tissue sarcoma. Treatment for EES commonly involves chemotherapy and surgical resection (ST) or less commonly combined chemotherapy, surgery, and radiotherapy (ST + RT). The purpose of the current study was to evaluate our institutional experience treating EES.

METHODS

We reviewed 36 (18 males:18 females) patients (mean age 30 years) with a nonretroperitoneal/visceral EES treated with either ST (n = 24, 67%) or ST + RT (n = 12, 33%). All patients were treated with chemotherapy, most commonly vincristine, doxorubicin, cyclophosphamide/ifosfamide and etoposide (VDC/IE, n = 23, 66%) Radiotherapy was mostly delivered preoperatively (n = 9). The mean follow-up was 8 years.

RESULTS

The 10-year disease specific survival for patients was 78%, with no difference in the survival between patients in the ST versus the ST + RT groups (83% vs. 71%, p = 0.86). There was no difference in the 10-year local recurrence (91% vs. 100%, p = 0.29) or metastatic free survival (87% vs. 75%, p = 0.45) between the ST and ST + RT groups.

CONCLUSION

The results of the current study highlight the ability to achieve excellent local control with chemotherapy and surgery for EES. We recommend for multidisciplinary management of patients with EES, including chemotherapy and surgery, with use of radiotherapy if there is concern for a potentially close margin of resection.

The Midwest Sarcoma Trials Partnership: Bridging Academic and Community Networks in a Collaborative Approach to Sarcoma

The treatment of sarcoma necessitates a collaborative approach, given its rarity and complex management. At a single institution, multidisciplinary teams of specialists determine and execute treatment plans involving surgical, radiation, and medical management. Treatment guidelines for systemic therapies in advanced or nonresectable soft tissue sarcoma have advanced in recent years as new immunotherapies and targeted therapies become available. Collaboration between institutions is necessary to facilitate accrual to clinical trials. Here, we describe the success of the Midwest Sarcoma Trials Partnership (MWSTP) in creating a network encompassing large academic centers and local community sites. We propose a new model utilizing online platforms to expand the reach of clinical expertise for the treatment of advanced soft tissue sarcoma.

Development and validation of a unifying pre-treatment decision tool for intracranial and extracranial metastasis-directed radiotherapy

Background

Though metastasis-directed therapy (MDT) has the potential to improve overall survival (OS), appropriate patient selection remains challenging. We aimed to develop a model predictive of OS to refine patient selection for clinical trials and MDT.

Patients and methods

We assembled a multi-institutional cohort of patients treated with MDT (stereotactic body radiation therapy, radiosurgery, and whole brain radiation therapy). Candidate variables for recursive partitioning analysis were selected per prior studies: ECOG performance status, time from primary diagnosis, number of additional non-target organ systems involved (NOS), and intracranial metastases.

Results

A database of 1,362 patients was assembled with 424 intracranial, 352 lung, and 607 spinal treatments (n=1,383). Treatments were split into training (TC) (70%, n=968) and internal validation (IVC) (30%, n=415) cohorts. The TC had median ECOG of 0 (interquartile range [IQR]: 0-1), NOS of 1 (IQR: 0-1), and OS of 18 months (IQR: 7-35). The resulting model components and weights were: ECOG = 0, 1, and &gt; 1 (0, 1, and 2); 0, 1, and &gt; 1 NOS (0, 1, and 2); and intracranial target (2), with lower scores indicating more favorable OS. The model demonstrated high concordance in the TC (0.72) and IVC (0.72). The score also demonstrated high concordance for each target site (spine, brain, and lung).

Conclusion

This pre-treatment decision tool represents a unifying model for both intracranial and extracranial disease and identifies patients with the longest survival after MDT who may benefit most from aggressive local therapy. Carefully selected patients may benefit from MDT even in the presence of intracranial disease, and this model may help guide patient selection for MDT.

Primary Pancreatic Undifferentiated Pleomorphic Sarcoma

Primary pancreatic sarcomas are rare malignancies with an incidence of 0.1%. This case report is of a 48-year-old man who presented with this condition. The patient's treatment plan consisted of distal pancreatectomy and splenectomy with intraoperative immunohistochemistry and adjuvant chemotherapy. To correctly identify and treat undifferentiated pleomorphic sarcoma, a stepwise strategy involving cross-sectional imaging and extensive histopathology analysis is necessary.

Development and validation of a recursive partitioning analysis-based pretreatment decision-making tool identifying ideal candidates for spine stereotactic body radiation therapy

BACKGROUND

This study was aimed at developing and validating a decision-making tool predictive of overall survival (OS) for patients receiving stereotactic body radiation therapy (SBRT) for spinal metastases.

METHODS

Three hundred sixty-one patients at one institution were used for the training set, and 182 at a second institution were used for external validation. Treatments most commonly involved one or three fractions of spine SBRT. Exclusion criteria included proton therapy and benign histologies.

RESULTS

The final model consisted of the following variables and scores: Spinal Instability Neoplastic Score (SINS) ≥ 6 (1), time from primary diagnosis < 21 months (1), Eastern Cooperative Oncology Group (ECOG) performance status = 1 (1) or ECOG performance status > 1 (2), and >1 organ system involved (1). Each variable was an independent predictor of OS (p < .001), and each 1-point increase in the score was associated with a hazard ratio of 2.01 (95% confidence interval [CI], 1.79-2.25; p < .0001). The concordance value was 0.75 (95% CI, 0.71-0.78). The scores were discretized into three groups-favorable (score = 0-1), intermediate (score = 2), and poor survival (score = 3-5)-with 2-year OS rates of 84% (95% CI, 79%-90%), 46% (95% CI, 36%-59%), and 21% (95% CI, 14%-32%), respectively (p < .0001 for each). In the external validation set (182 patients), the score was also predictive of OS (p < .0001). Increasing SINS<zaq;6> was predictive of decreased OS as a continuous variable (p < .0001).

CONCLUSIONS

This novel score is proposed as a decision-making tool to help to optimize patient selection for spine SBRT. SINS may be an independent predictor of OS.

Single and multi-fraction spine stereotactic body radiation therapy and the risk of radiation induced myelopathy

Purpose

This study reports on the risk of radiation-induced myelitis (RM) of the spinal cord from a large single-institutional experience with 1 to 5 fraction stereotactic body radiation therapy (SBRT) to the spine.

Methods and Materials

A retrospective review of patients who received spine SBRT to a radiation naïve level at or above the conus medullaris between 2007 and 2019 was performed. Local failure determination was based on SPIne response assessment in Neuro-Oncology criteria. RM was defined as neurologic symptoms consistent with the segment of cord irradiated in the absence of neoplastic disease recurrence and graded by Common Toxicity Criteria for Adverse Events, version 4.0. Rates of adverse events were estimated and dose-volume statistics from delivered treatment plans were extracted for the planning target volumes and spinal cord.

Results

A total of 353 lesions in 277 patients were identified that met the specified criteria, for which 270, 70, and 13 lesions received 1-, 3-, and 5-fraction treatments, respectively, with a median follow-up of 46 months (95% confidence interval [CI], 41-52 months) for all surviving patients. The median overall survival was 33.0 months (95% CI, 29-43). The median D0.03cc to the spinal cord was 11.7 Gy (interquartile range [IQR], 10.5-12.4), 16.7 Gy (IQR, 12.8-20.6), and 26.0 Gy (IQR, 24.1-28.1), for 1-, 3-, 5-fractions. Using an a/b = 2Gy for the spinal cord, the median single-fraction equivalent-dose (SFED₂) was 11.7 Gy (IQR, 10.2-12.5 Gy) and the normalized biological equivalent dose (nBED_2/2) was 19.9 Gy (IQR, 15.4-22.8 Gy). One patient experienced grade 2 RM after a single-fraction treatment. The cumulative probability of RM was 0.3% (95% CI, 0%-2%).

Conclusions

Spine SBRT is safe while limiting the spinal cord (as defined on treatment planning magnetic resonance imaging or computed tomography myelogram) D0.03cc to less than 14 Gy, 21.9 Gy, and 30 Gy, for 1, 3, and 5-fractions, consistent with standard guidelines.

Outcome and surveillance pattern in older GIST population

e24016

Background: Recent studies of patients (pts) with gastrointestinal stromal tumor (GIST) have included an older patient population. The majority of these have focused on treatment, but little is known regarding the optimal duration of surveillance following surgery for localized disease. Methods: We conducted a retrospective study of pts age 70 years (yrs) and above (≥) at diagnosis (dx), who underwent surgery for their localized GIST. Charts were reviewed of GIST diagnosed between 1992 to 2016, to allow at least 5 yrs for surveillance, if performed. Demographics were analyzed and pts were risk stratified using modified NIH criteria. Results: We identified 42 pts with a median age of 74 yrs (70 to 89 yrs) at dx. The majority of pts were male (31, 74%) and non-Hispanic White (37, 88%). Most pts had gastric GIST (25, 60%). The median resected tumor was 47 mm (range 6 to 190). Thirty-nine of 42 pts had margin status documented R0 resection. The median overall survival for all pts was 7.9 yrs (1.1 to 17.7), with median recurrence free survival 5.6 yrs (1.1 to 13.7). Only 4 of 16 (25%) pts died from GIST recurrence, and all were detected under 5 yrs from surgery. Fourteen of 34 pts (41%) who survived over 5 yrs from resection had extended surveillance imaging. Demographics and risk stratification are shown in Table. None of the 16 low risk pts developed recurrence, including 6 (38%) whose surveillance imaging continued beyond 5 yrs. Among 7 intermediate risk pts, only 1 pt (14%) extended surveillance imaging beyond 5 yrs. Two intermediate risk pts (29%) developed recurrence and were symptomatic at dx. One intermediate risk pt died from GIST metastasis within 1 yr from surgery. Seven of 19 (37%) high risk pts had surveillance imaging beyond 5 yrs following surgical resection. Seven high risk pts (37%) developed recurrence within median 5.6 yrs (1.6 to 13.7) from surgery; five of these were detected on imaging. In the high risk pts with recurrence, 5 had received adjuvant imatinib and 2 declined any systemic therapy. Three pts (16%) in the high risk cohort died from GIST. Conclusions: In this cohort of pts age ≥ 70 yrs with resected GIST, the majority of pts were symptomatic at relapse. Older pts who undergo surgery for low risk GIST may not require extended surveillance. Fit, older pts with high risk GIST may benefit from extended surveillance imaging, even if they received adjuvant imatinib.[Table: see text]

Development and Assessment of a Predictive Score for Vertebral Compression Fracture After Stereotactic Body Radiation Therapy for Spinal Metastases

IMPORTANCE

Vertebral compression fracture (VCF) is a potential adverse effect following treatment with stereotactic body radiation therapy (SBRT) for spinal metastases.

OBJECTIVE

To develop and assess a risk stratification model for VCF after SBRT.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study conducted at a high-volume referral center included 331 patients who had undergone 464 spine SBRT treatments from December 2007 through October 2019. Data analysis was conducted from November 1, 2020, to August 17, 2021. Exclusions included proton therapy, prior surgical intervention, vertebroplasty, or missing data.

EXPOSURES

One and 3 fraction spine SBRT treatments were most commonly delivered. Single-fraction treatments generally involved prescribed doses of 16 to 24 Gy (median, 20 Gy; range, 16-30 Gy) to gross disease compared with multifraction treatment that delivered a median of 30 Gy (range, 21-50 Gy).

MAIN OUTCOMES AND MEASURES

The VCF and radiography components of the spinal instability neoplastic score were determined by a radiologist. Recursive partitioning analysis was conducted using separate training (70%), internal validation (15%), and test (15%) sets. The log-rank test was the criterion for node splitting.

RESULTS

Of the 331 participants, 88 were women (27%), and the mean (IQR) age was 63 (59-72) years. With a median follow-up of 21 months (IQR, 11-39 months), we identified 84 VCFs (18%), including 65 (77%) de novo and 19 (23%) progressive fractures. There was a median of 9 months (IQR, 3-21 months) to developing a VCF. From 15 candidate variables, 6 were identified using the backward selection method, feature importance testing, and a correlation heatmap. Four were selected via recursive partitioning analysis: epidural tumor extension, lumbar location, gross tumor volume of more than 10 cc, and a spinal instability neoplastic score of more than 6. One point was assigned to each variable, and the resulting multivariable Cox model had a concordance of 0.760. The hazard ratio per 1-point increase for VCF was 1.93 (95% CI, 1.62-2.30; P < .001). The cumulative incidence of VCF at 2 years (with death as a competing risk) was 6.7% (95% CI, 4.2%-10.7%) for low-risk (score, 0-1; 273 [58.3%]), 17.0% (95% CI, 10.8%-26.7%) for intermediate-risk (score, 2; 99 [21.3%]), and 35.4% (95% CI, 26.7%-46.9%) for high-risk cases (score, 3-4; 92 [19.8%]) (P < .001). Similar results were observed for freedom from VCF using stratification.

CONCLUSIONS AND RELEVANCE

The results of this cohort study identify a subgroup of patients with high risk for VCF following treatment with SBRT who may potentially benefit from undergoing prophylactic spinal stabilization or vertebroplasty.

A phase 2 study of belinostat and SGI-110 (guadecitabine) for the treatment of unresectable and metastatic conventional chondrosarcoma

TPS11578

Background: Conventional chondrosarcoma (cCS) accounts for ̃25% of primary bone cancers and is the second most common primary bone tumor after osteosarcoma. Surgical resection is the primary treatment for localized disease. No FDA approved therapy exists for advanced disease and chemotherapy has marginal efficacy with ORR < 12%. IDH1/2 mutation is seen in 50% of cases. Epigenetic dysregulation is central to oncogenesis in both IDH1/2 mutant and wild-type CS. Pre-clinical studies from our group show that combination treatment with HDAC and DNMT inhibitors is significantly more effective at suppressing the growth of CS models in vitro and in vivo compared to either therapy alone. The combination regimen mediates anti-tumor effects on CS by induction of apoptosis, induction of tumor suppressor genes (eg. E-cadherin), the induction of interferon responsive genes (eg. IRF7, OASL, ISG15, DDX58) and reversal of global hypomethylated state. Based on these findings we have designed a phase 2 clinical trial with an HDAC inhibitor (belinostat) and a DNMT inhibitor (guadecitabine) in patients with advanced cCS. Methods: NCI # 10330 is a single-arm, multi-center, Simon 2-stage, phase 2 clinical trial evaluating belinostat and guadecitabine in patients with advanced cCS. Eligible patients will have biopsy proven cCS which is measurable by RECIST v1.1 and amenable to biopsy, ECOG PS ≤ 2, any number of prior treatments (including none). Patients will receive guadecitabine 45 mg/m2 SC followed by belinostat 1000 mg/m2 IV once daily on days 1-5 of a 28-day cycle. A safety lead-in and continuous toxicity monitoring rule will be applied. The primary endpoint will be ORR. Since chemotherapy is associated with an ORR of 8-12% and targeted agents have shown an ORR of 0% in cCS, we will consider an ORR of 8% as inactive while an ORR of 28% will suggest promising activity. A Simon 2-stage design is employed. The design calls for 26 patients. If ≥ 2 responses are observed among 13 patients in stage I, the study will proceed to full accrual. If ≥ 5 responses are seen among 26 patients, the study treatment is considered promising. This design has 85% power with α of 0.054 to test for a response rate of 8% vs 28%. Secondary objectives include safety, tolerability and PFS. All patients will undergo pre-treatment and on-treatment tumor biopsies. Paired tissue will be used for correlative analysis including: 1) whole exome sequencing/RNAseq to evaluate changes in gene expression in response to treatment, 2) multiplex IHC to interrogate the effect of combination therapy on tumor immune microenvironment and 3) a global DNA methylation assay to better understand the changes in epigenetic landscape in response to treatment. This study is open throughout the ETCTN (NCT04340843). Six of the planned 26 patients in the safety lead-in have been enrolled without DLT. Further accrual is on hold pending completion of the safety lead-in. Clinical trial information: 04340843.

P10015/SARC033: A phase 2 trial of trametinib in patients with advanced epithelioid hemangioendothelioma (EHE)

11503

Background: EHE is a rare vascular cancer arising in liver, lung, soft tissue and bone. The natural history of metastatic disease varies considerably from indolent growth over years to rapid growth with fatal outcome in months. Treatment of patients (pts) with metastatic EHE with antiangiogenic therapy induces tumor response in a minority of pts, and median PFS is 6-12 months. TAZ-CAMTA1 translocation results in activation of MAPK pathway and is an oncogenic driver in EHE. We sought to evaluate the effect of MEK inhibition using trametinib in pts with unresectable EHE. Methods: A phase 2 trial of trametinib 2 mg daily was conducted in pts with EHE though the Experimental Therapeutics Clinical Trials Network supported by NCI in collaboration with SARC. Additional support was provided by the EHE Rare Cancer Charity and the EHE Foundation. Pts had to have evidence of objective tumor progression or EHE-related pain requiring narcotics for relief prior to enrollment. Presence of TAZ-CAMTA1 translocation was analyzed by fusion-FISH after enrollment. Primary trial endpoint was objective response rate (ORR) per RECIST1.1 with at least 1 objective response required in the 1st 13 pts to expand enrollment to 27. The trial was amended after stage 1 to continue enrollment to 27 pts with TAZ-CAMTA1 detected by FISH with goal of >4 objective responses in this group. Secondary objectives were PFS and OS rates, safety and change in pt-reported global health and pain scores per PROMIS questionnaires. Results: 43 pts were enrolled between 6/2017 – 9/2020 across 10 sites and 41 started therapy. TAZ-CAMTA1 fusion was detected in 26, not detected in 7, test failed in 5 and was not performed due to insufficient tumor in 5. Median pt age was 54 (range 22-81 yrs) and 11 were >65 yrs; 25 were female; ECOG was 0 in 23, 1 in 16 and 2 in 3 pts. Most pts experienced reduction in tumor size. ORR per RECIST was 7% (3/41); in pts with TAZ-CAMTA1 detected, the ORR was 0% (0/26). Mean pain intensity and interference scores had a statistically significant improvement and global quality of life scores did not statistically change after 4 weeks of therapy. 17 pts remained on treatment > 6 months and 7 > 12 months. 25 pts stopped trametinib due to EHE progression, 6 died during treatment, 6 withdrew from treatment, 3 stopped drug due to adverse event and 1 is on treatment. The most common AEs related to trametinib were rash, fatigue, nausea/vomiting, diarrhea, alopecia and edema; Grade >3 AEs included anemia, dyspnea, hypoxia, hypotension, syncope and dermatitis. Conclusions: To our knowledge, this is the largest prospective clinical study focused on pts with EHE. Although the trial did not meet the ORR goal, stable disease > 6 months was seen in 40% of pts, and EHE-related pain improved on treatment. Trametinib was associated with expected cutaneous and GI adverse effects. Additional pt-reported outcomes and biomarkers of inflammation are undergoing analysis. Clinical trial information: NCT03148275.

A phase III study (APROMISS) of AL3818 (Catequentinib, Anlotinib) hydrochloride monotherapy in subjects with metastatic or advanced synovial sarcoma

11505

Background: AL3818 (Catequentinib, Anlotinib) is a novel, orally administered, small molecule tyrosine kinase inhibitor. The primary objective of this Phase 3 study is to evaluate the efficacy of AL3818 monotherapy in patients (pts) with synovial sarcoma (SS) comparing with dacarbazine in randomization setting. Methods: Patients with a diagnosis of synovial sarcoma requiring second line or further line treatment were eligible for enrollment. The regimen was a 21-day cycle with oral AL3818 administered on 14 days on and 7 days off. This phase 3 trial is randomized in 2:1 ratio of AL3818 comparing to dacarbazine with option of crossover after PD of dacarbazine treatment. Progression free survival (PFS) with Log Rank test is the primary endpoint and this trial for SS is currently completed enrolled in US and Italy. Results: Total 79 pts initiated treatment and are evaluable, 52 received AL3818 as treatment arm (T), and 27 received dacarbazine (D) as control arm (C). Arms T/C median ages were 40.5/42.0 years (range: 18-70+) and 20/16 (38.5%/59.3%) were male. Overall, PFS was 2.89 months (95% CI: 2.73 – 6.87) for AL3818 and 1.64 (95% CI: 1.45 – 2.70) for D. The PFS of study met the primary endpoint with a p-value of 0.0015 and a HR of 0.449 (95% CI: 0.270– 0.744). At the month 4, 6, and 12, the percentages of progression free patients for AL3818 were 48.1%, 42.3% and 26.9%; and for D were 14.85%, 11.1% and 3.7%. For grade 3 treatment-related adverse events, 12(23.1%) of pts experienced for AL3818 and 7(25.9%) of pts experienced for D. The most common AL3818 related grade 3 AEs were diarrhea (5.8%) and hypertension (3.8%). Conclusions: This phase III trial demonstrates improved disease control and superior progression free survival for AL3818 vs dacarbazine in advanced SS. In addition, the study further confirms the acceptable benefit-risk profile of AL3818 from the prior randomized Phase 2b soft tissue sarcoma study (NCT02449343). AL3818 is a meaningful treatment option for pts with advanced SS. Clinical trial information: NCT 03016819 Clinical trial information: NCT03016819.

Differential Outcomes and Biologic Markers of Radiation-Associated vs. Sporadic Osteosarcoma: A Single-Institution Experience

Background: Radiation-associated osteosarcoma (RAO) is a rare, life-threatening complication from radiation. Many physicians presume RAO has a worse prognosis than sporadic osteosarcoma (SO), although limited objective data exist. We conducted a retrospective study comparing these entities. Methods: We identified adults treated at our institution with osteosarcoma (1990-2016) and categorized tumors as SO or RAO based on location within a prior radiation field. We extracted data on demographics, treatment and primary malignancy and examined available tumor samples for MTA-1 and ezrin using immunohistochemistry (IHC). Results: Of 159 identified patients, 28 had RAO, diagnosed at a median interval from radiation of 11.5 years (1.5-28 years). Median follow-up was 2.8 years (0.1-19.6 years). Median progression free survival (PFS) and overall survival (OS) were not significantly different in the small population of patients with metastases, SO (n = 20) vs. RAO (n = 6): PFS 10.3 months vs. 4.8 months (p = 0.45) and OS 15.6 months vs. 6.1 months (p = 0.96), respectively. For the larger group with localized disease, median relapse-free survival (RFS) and OS were significantly different, NR vs. 12.2 months (p < 0.001) and NR vs. 27.6 months (p = 0.001) in SO (n = 111) vs. RAO (n = 22), respectively. On IHC, there were significant differences in distribution of high, intermediate or low MTA-1 (p = 0.015) and ezrin (p = 0.002) between RAO and SO tumors. Conclusions: Patients with metastases at diagnosis fared poorly irrespective of prior radiation. RAO patients with localized disease had worse outcomes without detectable differences in therapy rendered or treatment effect in resected specimens. Higher expression of MTA-1 in RAO patients may suggest an underlying difference in tumor biology to explain differences in outcomes.

Current clinical management of primary cardiac sarcoma

Introduction: Primary cardiac tumors are exceedingly rare, with approximately 75% representing benign lesions. Sarcoma represents the most common primary cardiac malignancy, with a wide range of sarcoma histologies represented. Symptoms at diagnosis vary based on tumor location. Multidisciplinary treatment including chemotherapy, surgery, and occasionally radiation is often warranted. Despite aggressive treatment, the overall prognosis for primary cardiac sarcoma (PCS) remains poor with a median survival of approximately 1 year.Areas covered: A PubMed search for the key terms; 'cardiac sarcoma', 'primary cardiac sarcoma', and 'treatment' were conducted. Abstracts were reviewed for reports on presentation, treatments, and outcomes in PCS. Available data was limited to single-institution series, most of which were retrospective. Patterns of symptoms at diagnosis varied with tumor location (right vs. left vs. pericardium). Multimodality therapy, including chemotherapy and surgical resection was most commonly reported. Completely negative margin (R0) resection has the greatest impact on overall survival.Expert opinion: Given the rarity of PCS, patients should be referred to a high-volume sarcoma center for multidisciplinary evaluation. Neoadjuvant chemotherapy should be considered to aid in surgical resection. Due to the propensity for brain metastases in cardiac tumors, brain MRI at the time of diagnosis should be considered.

Burden of Cardiac Arrhythmias in Patients With Anthracycline-Related Cardiomyopathy

OBJECTIVES

The objective of this study was to determine the incidence of arrhythmias and device (internal cardiac defibrillator/cardiac resynchronization therapy defibrillator) therapies in patients with a diagnosis of cardiomyopathy and anthracycline exposure.

BACKGROUND

The burden of arrhythmias in adult cancer survivors with anthracycline-related cardiomyopathy has not been studied, but might have important implications for clinical management and outcomes.

METHODS

Retrospective cohort study of all patients with left ventricular dysfunction (LVD) who underwent internal cardiac defibrillator/cardiac resynchronization therapy defibrillator implantation at the Mayo Clinic from 1990 to 2012. Ninety-five patients were cancer survivors (on average, 5 years), 23 of which had anthracycline-related cardiomyopathy (CA-ACM) and 72 of which had non-anthracycline-related cardiomyopathy (CA-NACM). A second control group of 68 noncancer patients with ischemic heart disease-related LVD or dilated cardiomyopathy (ischemic heart disease [IHD]/DCM) was age- and gender-matched to patients with CA-ACM. All patients were followed for arrhythmias and appropriate ICD therapies, total mortality, heart transplantation, and left ventricular ejection fraction.

RESULTS

More than 5.5 ± 3.0 years after device implantation, nonsustained ventricular tachycardia was the most common arrhythmia in patients with CA-ACM followed by atrial fibrillation and sustained ventricular tachycardia or fibrillation (73.9%, 56.6%, and 30.4%, respectively), which was not significantly different from CA-NACM and IHD/DCM. The 5-year rate of ICD therapies was 19.9% in the CA-ACM group versus 22.1% in the CA-NACM group and 32.6% in the IHD/DCM group (p = NS for both). Device therapy-free, heart transplantation-free, and/or overall survival as well as cardiac function dynamics over time were not different in patients with CA-ACM than in patients with CA-NACM and IHD/DCM.

CONCLUSIONS

This study indicates that the burden of arrhythmia in patients with anthracycline-related cardiomyopathy is not different from cancer and non-cancer patients with IHD-related LVD or DCM.